Mark R. Geier

Mark Robin Geier (born 1948) is an American former physician and controversial professional witness who testified in more than 90 cases regarding allegations of injury or illness caused by vaccines. Since 2011, Geier's medical license has been suspended or revoked in every state in which he was licensed over concerns about his autism treatments and his misrepresentation of his credentials to the Maryland Board of Health, where he falsely claimed to be a board-certified geneticist and epidemiologist.

Mark and his son David are frequently cited by proponents of the now-discredited claim that vaccines cause autism. Geier's credibility as an expert witness has been questioned in 10 court cases. In 2003, a judge ruled that Geier presented himself as an expert witness in "areas for which he has no training, expertise and experience." In other cases in which Geier has testified, judges have labeled his testimony "intellectually dishonest," "not reliable" and "wholly unqualified." Another judge wrote that Geier "may be clever, but he is not credible."

Geier's scientific work has also been criticized; when the Institute of Medicine reviewed vaccine safety in 2004, it dismissed Geier's work as seriously flawed, "uninterpretable", and marred by incorrect use of scientific terms. In 2003, the American Academy of Pediatrics criticized one of Geier's studies, which claimed a link between vaccines and autism, as containing "numerous conceptual and scientific flaws, omissions of fact, inaccuracies, and misstatements." In January 2007, a paper by the Geiers was retracted by the journal Autoimmunity Reviews. New Scientist reported that the supposed institutional review board (IRB) that Geier claimed approved his experiments with autistic children was located at Geier's business address and included Geier, his son and wife, a business partner of Geier's, and a plaintiff's lawyer involved in vaccine litigation. The Maryland State Board of Physicians referred to it as a "sham IRB" that did not meet the requirements of state or federal law.